This invention relates to improvements in methods and apparatus for the formed-in-situ installation of localised repairs or reinforcements in pipes, conduits and the like. In particular, it relates to so-alled trenchless technology methods in which a repair or reinforcement is installed in a pipe or conduit by operating from one or more of its ends and without the need to expose or break it, and so-called soft repair systems in which a pipe or conduit is repaired or reinforced by the installation internally of a sleeve, formed in-situ from fibrous reinforcement material impregnated with a settable resin, said repair or reinforcement being maintained in position in intimate contact with the inner wall of the pipe of conduit during the process of curing said settable resin by the pressure of an inflated tube or bag.
In the operation and maintenance of pipes and conduits, such as sewers, water mains, gas mains and the like, it is often necessary to effect repairs. Damage to such pipes and conduits in subterranean situations is most commonly caused by localised ground movement, by differential movement between main and tributary lines, by generalised corrosion and by erosion resulting from localised flow impingement. Modern environmental protection policies deem leakage from or into such pipes or conduits to be unacceptable and it is usual for operators to be required to repair such damage when it is detected. As a result, localised, in-situ repairs to subterranean and otherwise inaccessible pipes and conduits are frequently necessary and a variety of so-called trenchless technology methods have been developed for this purpose.
A particular problem in sewerage systems is the fracturing of tributary service connections at or close to the sewer main. While the sewer main is normally laid on a prepared foundation and, as a result, is positionally stable, service connections are merely laid in trenches and cut into the main if unplanned or connected to an oblique junction pipe if planned. Subsidence of the principal part of a service connection then causes it to fracture away from the part secured to the main. Other common forms of damage are the fracturing of boundary traps as a result of plunging by plumbers to clear blockages, differential settlement causing fractures in a line and inadequate jointing allowing penetration of tree roots.
A variety of methods have been developed for the localised in-situ repair of sewers. Where a repair is required in a pipe or conduit to which direct access is available, such as a sewer main, apparatus and method such as that disclosed in Australian Patent No. 35101/93 might be employed. This patent discloses an inflatable form upon which the settable resin-impregnated repair material is assembled, the whole then being winched into position at the proposed repair site. The inflatable form is then inflated with a flow of hot water, bringing the repair material into intimate contact with the inner wall of the sewer and maintaining it in position until curing is complete. The inflatable form is then deflated and withdrawn, leaving the cured repair in place. Where a repair is required to a tributary service connection, to which direct access is more difficult to obtain, apparatus and method such as that disclosed in Australian Patent No. 49722/93 might be employed. In this method, a launcher unit is positioned in a sewer main adjacent a tributary service connection opening. Fluid pressure is then employed to project a closed-ended tube of fibrous reinforcement material impregnated with a settable resin from the launcher and evert it into the service connection. Eversion pressure is sustained to maintain the repair material in place and in intimate contact with inner surface of the service connection until curing is complete. The launcher is then removed and the closed end of the repair cut out to re-open the service connection.
This latter method requires the tube of reinforcement material to be of sufficient length to extend from the sewer main to beyond the site of the repair. Therefore, although the repair itself may need to be only a meter or so in length to achieve its intended purpose, if the repair site is located some distance from the main, it must be made wastefully long. Additionally, if the site of the repair in the tributary service connection is remote from the sewer main, it may be necessary for the repair material, during its eversion, to traverse junctions and bends of small radius, such as traps. This cannot be achieved reliably by the method. Similar difficulties exist in attempting to position repair material from the service end of the tributary service connection.
The object of the present invention is to provide an apparatus and method for the reliable installation of localised, formed-in-situ repairs or reinforcements anywhere in an extended pipe, conduit or the like, regardless of the need to traverse junctions or bends of small radius and without the need to break said pipe, conduit or the like.
According to the present invention, a tube of soft, fibrous reinforcement material is impregnated with a settable resin and installed in the appropriate position within an installation sleeve made from a suitable soft, flexible and impervious material. Said reinforcement material is secured to the inner surface of said installation sleeve with a peelable adhesive or the like. Said installation sleeve is made with one closed end, to which is attached internally and extending through the length of said installation sleeve and for a suitable distance beyond its open end, a guiding means, such as a light, flexible and strong guide tape or cord. Attached externally to said closed end and with a length suitably exceeding that of said installation sleeve, is a light, flexible and strong withdrawing means, a retrieval tape or cord for example. Said closed end of said installation sleeve is provided with one or more calibrated vent openings.
The assembly of reinforcement material and installation sleeve is rolled onto a drum, commencing first with the free end of said retrieval tape or cord, followed by said installation sleeve which is wound on commencing with its said closed end. Said drum is then placed on a shaft within a closed, pressurisable container, said guide tape or cord and the open end of said installation sleeve being led out through a radially-positioned delivery tube, at the proximal end of which are provisions which act to collapse said installation sleeve into a compact form. Obviously, said drum might be left in place in said pressurisable container and said retrieval tape or cord and said installation sleeve connected to a short bridle led in through said delivery tube and attached to said drum and said assembly of installation sleeve and reinforcement material drawn in through said delivery tube and onto said drum by rotation of said drum. Said delivery tube comprises a short length fixed to said pressurisable container and one or more removable extension parts made in whatever length is required to reach an access opening into a tributary service connection to be repaired or reinforced. The open end of said installation sleeve is then securely and sealingly attached to the distal end of said delivery tube and said guide tape or cord is coiled outside the end of said delivery tube in preparation for its deployment. Following suitable cleaning of said tributary service connection, the distal end of said delivery tube is positioned in alignment with and in close proximity to the said access opening into the service end of said tributary service connection and said guide tape or cord is released into said tributary service connection and carried through it by a copious flow of water into the sewer main and thence downstream to the nearest manhole, where it is secured. If necessary, a light draw cord is first flushed through said tributary service connection and used to draw said guide tape or cord through behind it. Said pressurisable container is then pressurised with a cool pressurising medium and said drum controllably rotated in the appropriate direction, causing said installation sleeve, under the influence of the pressurised medium within said pressurisable container, to evert from said delivery tube directly into said access opening of said tributary service connection, the rate of eversion being regulated by a first operator controlling rotation of said shaft upon which said drum is supported and the pressure of said cool pressurising medium, the slack of said guide tape or cord being taken up by a second operator positioned at said downstream manhole in said sewer main. As said installation sleeve progressively everts through said tributary service connection, the pressure within said pressurisable container is transmitted throughout its everted length, which is inflated into intimate contact with the inner surface of said service connection, and continues to act upon the everting zone of said installation sleeve, thereby impelling the eversion of said installation sleeve and drawing with it through its interior its collapsed part which contains, in the appropriate location, said impregnated reinforcement material. Where the everting end of -said installation sleeve is required to traverse a feature in said service connection which imposes an impediment to its progression, tension applied by said second operator to said guide tape or cord assists it to do so. At the point where that part of the collapsed said installation sleeve containing said impregnated reinforcement material reaches said eversion zone of said installation sleeve, attached as it is to said installation sleeve by said strippable adhesive or the like, said reinforcement material is everted with said installation sleeve and is thereby brought into intimate contact with the inner surface of said tributary service connection, where it is maintained by the inflation of said everted part of said installation sleeve. Progressive eversion of said installation sleeve is then continued until its said closed end is fully everted, whereupon its movement ceases. Only said retrieval tape or cord passes along said delivery tube during the final stage of eversion of said installation sleeve. A flow of heated pressurising medium, such as steam, hot water or the like is then admitted to said pressurisable container, from whence it passes along the length of said everted installation sleeve to emerge at said calibrated vent openings in its said closed end, pressure within said installation sleeve being regulated to an appropriate figure by adjustment of the rate of inflow of said cool and heated pressurising media to said pressurisable container. The inflation pressure within said installation sleeve acts to maintain said impregnated reinforcement material in place in intimate contact with the inner wall of said tributary service connection whilst heat from said flow of heated pressurising medium acts to accelerate the curing of said settable resin with which said reinforcement material is impregnated. Where appropriate, tension is maintained on said retrieval tape of cord during the said curing process to restrain said installation sleeve against extension whilst it is heated and pressurised. When said settable resin with which said reinforcement material is fully cured, the flow of said pressurising media is terminated, said pressurisable container is depressurised and said installation sleeve is de-everted by tension applied to the proximal end of said retrieval tape or cord, said installation sleeve peeling away from said cured repair as its point of de-eversion progressively passes said cured repair. Said guide tape or cord is released at said downstream manhole and is drawn back with said installation sleeve. Said installation sleeve, guide tape or cord and retrieval tape or cord are then cleaned, inspected, repaired as required and stored for future use.